Meniscus Phenomenon in Longitudinal Tracheid of Pinus

摘要

An experiment was conducted to know the safranine impregnation behavior in different softwood species. 1200x magnification was used to see the safranine penetration pathway in longitudinal direction especially in longitudinal tracheid. Safranine impregnation in longitudinal tracheid was captured in digital video mode at 1200x magnification. Form that file, the formation of curved and flat air-safranine meniscus were observed easily. Considering the tracheid radius 16-20 μm, surface tension of water at 72dynes/cm at 23℃ and a contact angle 30°, the capillary pressure range was found 0.06-0.08 bar. Lower the lumen diameter, higher the capillary pressure. Longitudinal tracheid forms a capillary tube by interconnecting them with pits. Due to the difference of total pressure of water just under the safranine-water interface and total pressure of the air just above the interface, curved meniscus is formed in the lumen of longitudinal tracheid. For the pit aspiration, the pressure of safranine and air in the lumen of tracheid was found equal which the reason was behind to get the air-safranine meniscus flat.